Automatic service conduit connector devices for railway vehicle couplings

ABSTRACT

Automatic connectors for service conduits associated with automatic railway vehicle couplings are in this invention displaceable relative to the respective coupling heads into engagement with each other in response to the approach of the coupling heads to interengagement, by a mechanical lever system such that the final interengagement of the connectors occurs only after the frontal impact between the coupling heads.

Unit'edStates Patent lnventors Aldo Gnavi;

Giacomo Di Bartolomeo, both of Turin,

Italy Appl. No. 13,412

Filed Feb. 24, 1970 Patented Jan. 11, 1972 Assignee Compagnia ItaliansWestinghouse Freni E.

Segnali Turin, Italy Priority Feb. 25, 1969 Italy 50724-A/69 AUTOMATICSERVICE CONDUIT CONNECTOR DEVICES FOR RAILWAY VEHICLE COUPLINGS 6Claims, 8 Drawing Figs.

US. Cl

213/100 W Int. Cl 861g 5/06, 861g 5/10 so] neuorsmch 21311.3.

[56] References Cited UNITED STATES PATENTS 3,421,636 1/1969Dufonrmantel 2l3 /l.3 2,229,902 1/1941 Robinson 213/76 2,751,089 6/1956Scharfenberg. 213/1 .3 3,387,714 611968 Dawson 213/76 Primary Examiner--Drayton E. Hoffman Attorney-Sughrue, Rothwell, Mion, Zinn & MacpeakABSTRACT: Automatic connectors for service conduits associated withautomatic railway vehicle couplings are in this invention displaceablerelative to the respective coupling heads into engagement with eachother in response to the approach of the coupling heads tointerengagement, by a mechanical lever system such that the finalinterengagement of the connectors occurs only after the frontal impactbetween the coupling heads.

PATENTED JAN] 1 1972 SHEET 2 OF 8 PATENTED JAN 1 1972 3633; 762

snmsura PATENTED N 1 i9 2 SHEET '3 [IF 8 PATENTED JAM 1 I972 SHEET 5 OF8 PATENTED Jam 1 mg 3,633,7 2 SHEET 7 OF 8 AUTOMATIC SERVICE CONDUKTCONNECTOR DEViCES FOR RAILWAY VEHICLE COUPLINGS This invention relatesto automatic connector devices for effecting automatic service conduitconnections in automatic couplings for railway vehicles.

In order to couple two railway vehicles together automatically it is ingeneral necessary to effect (a) automatic interengagement of mechanicalcouplings for transmitting both pulling and pushing forces between thevehicles, and (b) automatic interconnection of service conduits such aselectrical cables and pneumatic or vacuum lines.

Among the conditions laid down for European push/pull automaticcouplings by the U.I.C. (Union international Chemins de Fer) inagreement with the 0.5.1 .D. (Organizzazione per la collaborazione delleferrovie), as issued by the Soviet Union, there is included the specificrequirement that such couplings must be capable of direct coupling tothe SA-3 type coupling used in the U.S.S.R. and having the so-calledWillison profile.

This invention relates particularly to automatic connector devices forservice conduits for use in conjunction with automatic railway vehiclecouplings of the aforementioned Willison type. It is well known that inautomatic couplings of this type interengagement of two coupling headsis accompanied by lateral displacement of the heads, in oppositedirections, typically by about 40 mm. This displacement increasesconsiderably the difliculty of achieving satisfactory automaticinterconnection of service conduits associated with each coupling head.Moreover, the relative speed of the vehicles immediately precedingcoupling thereof can be quite high.

in arranging for automatic interconnection of service conduits thefollowing factors must be taken into account: (i) the group of serviceconduit connectors carried by each coupling head follows, in general,the movements of the coupling head;

(ii) the service conduit connectors, during the approach of two couplingheads to automatic mechanical interengagement, may not be aligned, dueto misalignment of the coupling heads during this approach; (iii) at theinstant of interengagement of the coupling heads the service conduitconnectors must be accurately aligned with each other to avoid frictionbetween the respective end seals of the connectors after interengagementof the connectors.

It follows from factors (ii) and (iii) above that if the service conduitconnectors of the automatic coupling approach each other at an excessivespeed it is difficult to ensure that the interengaging connectors of thecoupling heads are correctly aligned upon mechanical coupling of saidheads. This difficulty is increased when a severe impact occurs betweenthe connectors when the coupling heads collide with each otherfrontally, prior to the lateral shifting of the heads mentionedpreviously.

An object of the present invention is to provide an improved automaticconnector device for a railway vehicle automatic coupling, in whichreliable interconnection of service conduits can be effectedautomatically in operation of the coupling. More particularly, theinvention aims to avoid or minimize the above-mentioned difficultiesassociated with such connector devices.

The invention accordingly provides device for effecting automaticservice conduit connections in an automatic coupling for railwayvehicles of the kind having interengageable coupling heads with frontalimpact faces, characterized in that each coupling head has a conduitconnector member associated therewith and displaceable relative to thehead in a direction substantially perpendicular to the frontal impactface of the respective head, and characterized by means responsive tothe approach to coupling of two such cooperating coupling heads toeffect relative movement between the respective connector members andthe respective coupling heads so as to efiect operative inter-engagementof said connector members only after impact of the two frontal impactfaces of the coupling heads has occurred.

The invention will now be described, by way of nonlimiting example, withreference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic plan view of an automatic couplingincorporating automatic connector devices according to one embodiment ofthe invention, in its initial position at the start of the couplingoperation;

FIG. 2 is a plan view of the coupling of HO. 1, in an intermediate phaseduring the approach of the two coupling heads, after a first phase ofthe coupling operation;

FIG. 3 is a plan view of the said coupling at a further phase of theautomatic coupling operation, immediately after the frontal impact ofthe coupling heads;

FIG. 4 is a plan view of the said coupling in its coupled state afterthe final coupling phase, and

F168. 5, 6, 7 and 8 are diagrammatic plan view, corresponding to FIGS 1,2, 3 and 4 respectively, of a coupling incorporating connector devicesaccording to another embodiment of the invention, in four successivephases of the coupling operation.

The arrangement and operation of the coupling shown in FIGS. 1 to 4 willfirst be described.

The coupling comprises two identical coupling heads 1, 2 shown in brokenoutline, each of the Willison profile.

Upon the initial approach of the coupling heads 1, 2 towards each other,respective forwardly extending hornlike projections 3, 4 on the heads 2,1 initially make contact with respective arms 5a, 6a of respectivesensing levers 5, 6 pivoted about fixed pivot pins 9, 10 on therespective heads 1, 2, causing initial rotation of said sensing levers5, 6 anticlockwise (as viewed).

Referring to the respective coupling head 1; 2, each sensing lever 5; 6has a further arm 11; 12 which provides a support for relative slidingmovement of a guide rod 13; 14 which is pivotally connected at a pivotpin 17; 18 to an intermediate point on a respective operating lever 15;16 and which is surrounded by a respective helical spring 27; 28. Thespring 27; 28 urges the lever arm 11; 12 away from the operating lever15; 16.

The operating lever 15; 16, which is also pivoted about the pivot pin 9;10, has a rounded free end 19; 20 which lies between a respective pairof external lugs 31, 41; 32, 42 provided on the casing of a connectormember 7; 8. The connector member 7; 8 is carried by the coupling head1; 2 and is displaceable relative thereto in a direction substantiallyperpendicular to a respective frontal impact face 63; 64 of the head 1;2. Each connector member 7; 8 carries a group of service conduitconnectors, including, for example, electrical, pneumatic and vacuumline couplings, known per se.

The operating lever 15; 16 is provided, intermediate the pivot pin 17;18 and the free end 19; 20, with a pin 45; 46 which engages in a slot47; 48 formed at one end of a stop link 49; 50, forming a lost motionconnection between the lever 15; 16 and the link 49; 50. The stop link49; 50 carries at its opposite end a pin 53; 54 which forms a pivotconnection between the stop link 49; 50 and a toggle link 55; 56, thelatter being pivotally connected to the respective coupling head 1; 2 bya pivot pin 57; 58. The links 49, 55; 50, 56 form a respective togglelinkage which is biased into locked position by a helical spring 59; 60anchored to the head 1; 2 at 61; 62. ln this locked position the pivotpin 57; 58 is displaced from the line interconnecting the pins 45, 53;46, 54 on the side thereof such that a traction force (i.e., to the leftas viewed) along said line gives rise to a moment about the pivot pin57; 58 in the same sense as that due to the spring 59; 60.

Upon the above-mentioned initial anticlockwise rotation of each sensinglever 5; 6, which takes place against the action of a respective returnspring 21; 22 interconnecting a pin 25; 26 on the sensing lever arm 11;12 and a fixed pin 23; 24 on the head 1; 2, the spring connector 13; 14causes the respective operating lever 15; 16 to make a small initialmovement, anticlockwise as viewed, until the pin 45; 46 is located atthe end of the slot 47; 48 remote from the pivot pin 57; 58, whereafterfurther movement of the operating lever 15; 16 and, therefore, of theconnector member 7; 8 is prevented by the stop link 49; 50 in itsblocking position. This is the position shown in FlG.

2, at the end of the first phase of relative movement of the connectormember 7; 8 and the respective coupling head 1; 2.

As each coupling head 2; l advances further towards the other theprojection 3; 4 causes further rotation of the sensing lever 5; 6anticlockwise. This rotation, as a consequence of the aforesaid blockingaction of the stop link 49; 50 on the operating lever 15; 16, causesfurther compression of the spring 27; 28 between the lever arm 11; 12and the pivot pin 17; 18, until the free end of the lever arm 11; 12,which is rounded, abuts an intermediate land 51; 52 on the stop link 49;50. This is the position shown in FIG. 3, and is reached immediatelyafter frontal impact of a protuberance 35; 36 of the coupling head 1; 2against a bottom surface 64; 63 of the other head 2; 1 has occurred. Itwill be noted that the blocking of the operating lever 15; 16 by thestop link 49; 50 takes place before the frontal impact: this preventsthe transmission to the connector member 7; 8 and its associateddisplacing mechanism of shocks, which would otherwise result from saidimpact.

Adjustment of the initial angular position of the lever arm 11; 12relative to the operating lever 15; 16 can be effected by adjustment ofthe position of a stop nut 43; 44 carried on the free end of the guiderod 13; 14, which is threaded. Such adjustment ensures that theoperating lever 15; 16 is blocked by the stop link 49; 50 before frontalimpact of the heads I; 2 takes place.

Further advance of each coupling head I; 2 towards the other isaccompanied by lateral sliding movement along the frontal impact face63; 64 of the protuberance 36; 35 of the other head 2; 1, until the twoheads 1; 2 are fully interengaged, when the protuberances 35; 36 of theheads 1; 2 will be located behind respective projecting noses 38; 37 ofthe heads 2; 1. The two connector members 7; 8 are then coaxiallyaligned. This final phase of the coupling operation is accompanied by afurther slight anticlockwise rotation of the sensing lever 5; 6, whichcauses the lever arm 11; 12 to rock the stop link 49; 50 in ananticlockwise direction about the pin 45; 46. When the pivot pin 57; 58passes, as a result of this movement, over to the other side of the linejoining the pins 45; 46 and 53; 54, the toggle 49, 55; 50, 56 becomesunstable and is broken or released, thereby permitting movement of thestop link 49; 50 from its blocking position. When the stop link 49; 50is thus released the energy stored in the spring 27; 28 causesanticlockwise rotation of the respective operating lever l5; 16 (asviewed), the strength of the spring 27; 28 being greater than that ofthe spring 59; 60. Consequently the connector member 7; 8, which is nowcoaxially aligned with the other connector member 8; 7, is advancedrelative to the coupling head 1; 2 so that the two connector members 7;8 operatively interengage. This is illustrated in FIG. 4, whichrepresents the end of the final stage of the coupling operation.

When the vehicles joined by the coupling are to be uncoupled, thecoupling heads 1, 2 are disengaged from each other by the action of arelease mechanism, not shown. When the uncoupled vehicles separate, thecoupling heads 1, 2 recede fromeach other, so that when the projection3; 4 of the head 2; 1 moves from the position shown in FIG. 4, thesensing lever 5; 6 of the other head 1; 2 rotates clockwise, as viewed,about the pivot pin 9; under the action of the return spring 21; 22,towards the position shown in FIG. 1.

As a result of this return movement of the sensing lever 5; 6 thecompression of the spring 27; 28 is relieved, the latter returning tothe position of maximum distension shown in FIGS. 1 and 2, in which thestop nut 43; 44 on the guide rod 13; 14 comes into contact with thesensing lever arm 11; 12. The continued clockwise rotation of thesensing lever 5; 6 carries with it the operating lever 16 by virtue ofthe now rigid connection afforded by the guide rod 13; 14, and this inturn causes retraction of the connector member 7; 8 relative to the headI; 2, disengaging the connector members 7; 8 from each other.

During this movement of the operating lever 15; 16 the stop link 49; 50is displaced simultaneously in the same direction under the influence ofthe spring 59; 60 acting through the toggle link 55; 56. However, thepin 45, 46 remains at the end of the slot 47; 48 in the stop link 49; 50remote from the respective pivot pin 57; 58. Upon completion of themovement of the stop link 49; 50 the pivot pin 53, 54 is sufficientlydisplaced to enable the spring 59; 60 to return the toggle link 55; 56to its stable locked position (FIGS. l-3). The continued clockwiserotation of the operating lever 15; 16 causes the pin 45; 46 to move tothe opposite end of the slot 47; 48 nearest the pivot pin 57; 58.

It will be seen that the various components of the coupling head 1; 2have resumed automatically the original positions of FIG. 1, the returnspring 21; 22 ensuring that the end of the sensing lever arm ll; 12 iswithdrawn from engagement with the intermediate land 51; 52 of the stoplink 49; 50.

In the embodiment of FIGS. 5, 6, 7 and 8 components corresponding to theembodiment of FIGS. 1 to 4 are indicated by the same reference numerals.

In this embodiment the stop link 49; 50 is replaced by a stop lever 49';50' pivoted at one end by a pivot pin 57'; 58" to the coupling head 1; 2and provided at its other end with a hooklike tooth 65; 66 adapted toengage a cooperating hooked end 79; of one arm 15a; 16a of the operatinglever 15; 16 to block the operating lever.

FIG. 5 shows the two coupling heads 1, 2 in the initial phase of thecoupling operation, in which the projection 3; 4 of each head 2; 1 hasjust made contact with the end of the sensing lever arm 5a; 6a duringthe approach of the coupling heads.

Analogously to the operation of the previously described embodiment theanticlockwise rotation of the sensing lever 5; 6 caused by the initialapproach of the coupling heads causes anticlockwise rotation of theoperating lever l5; 16 through the action of the spring 27; 28, and thisin turn advances the connector member 7; 8 relative to the coupling headI; 2.

The clockwise rotation of the operating lever 15; 16 is halted by theengagement of the hooked end 79; 80 of the arm 15a; 16a with the tooth65; 66 of the stop lever 49; 50', the latter being held in its blockingposition by a biassing spring 59'; 60' attached to an intermediate pin53; 54' carried by the lever 49; 50' and anchored at its other end to apin 61 62' on the head I; 2. This intermediate phase of the couplingoperation, in which advance of the connector member 7; 8 is halted, isillustrated in FIG. 6. Further advance of the coupling head I; 2 towardsthe other head 2; 1 causes further compression of the spring 27; 28while the operating lever 15; 16 remains blocked by the stop lever 49;50, until the impact face 63; 64 of the head 1; 2 collides with theprotuberance 36; 35 of the other head 2; l; the condition of the heads1; 2 immediately after the frontal impact therebetween is shown in FIG.7.

In the final phase of the coupling operation, the protuberance 35; 36 ofthe head 1; 2 slides laterally on the impact face 64; 63 of the otherhead 2; 1 until it is behind the inwardly projecting nose 38; 37 of thelatter. During this movement of the coupling head 2; 1 the laterallyoutwardly facing surface of the protuberance 36; 35 engages a roundedprojecting end 75; 76 of a plunger 67; 68 mounted for axial slidingmovement in a wing 39, 40 of the coupling head 1; 2. The other end ofthe plunger 67; 68 bears against an intermediate land 51'; 52 on thelocking lever 49'; 50, the biassing spring 59'; 60' urging the plunger67; 68, through the lever 49'; 50, into its projecting position, inwhich a flange 71; 72 carried by the plunger 67, 68 engages a stopsurface 73; 74 in the wing 39; 40 of the coupling head 1; 2.

As the protuberance 36; 35 of the coupling head 2; 1 slides laterally onthe impact face 63; 64 of the head 1; 2 the plunger 67; 68 is urgedagainst the land 51; 52', rocking the stop lever 49', 50 clockwiseagainst the action of the spring 59'; 60', until the connector member 7is coaxially aligned with the connector member 8. At this stage thetooth 65; 66 releases the hooked end 79; 80 of the operating lever,permitting anticlockwise rotation of the operating lever l5; 16 underthe action of the spring 27; 28. This causes interengagement of the end33 of the connector member 7 with the cooperating end 34 of the alignedconnector member 8. The coupling heads I and 2 are then fullyinterengaged, as shown in FIG. 8.

The mechanical arrangement for halting the advance of the connectormembers relative to their respective coupling heads after an initialmovement of the respective operating lever in response to the initialengagement of the approaching coupling heads, and prior to impact of theheads on each other, may take other forms. For example a stop member maybe pivoted at one end on the operating lever and provided at its otherend with a tapering slot in which there is located a fixed pivot pinjoined to the respective coupling head. The stop member may be biassedby a spring to assume, during the initial unobstructed movement of theoperating lever in the first phase of the coupling operation, a positionin which said fixed pivot pin occupies the narrowest portion of theslot. At the start of the final stage of the coupling operation, afterthe frontal impact of the two coupling heads, the slot of the stopmember is shifted to a position in which the fixed pivot pin occupiesthe widest portion of the slot.

The automatic connector devices herein described permit movement of theconduit connector members of the coupling towards each other in threesuccessive stages: a first rapid ad vance of the connector memberstowards each other, effected by the initial contact between the couplingheads; an intermediate phase in which advance of the connector membersrelative to the coupling heads is stopped, and a final, relativelyslower, advance of the connector member to union therebetween afterimpact between the coupling heads. The control of the connector memberscan be effected by a pneumatic control device comprising a cylinderanchored at one end to the respective coupling head and having a pistonsliding therein and connected to the operating lever. A controlled airleak from the compressed air chamber of the cylinder may take placethrough a controlled restrictor, so that the flow resistance of saidrestrictor increases asymptotically with the piston position towards theend of the coupling stroke of the piston.

We claim:

1. In an automatic railway vehicle coupling having in terengageablecoupling heads with frontal impact faces, and associated serviceconduits, a device for effecting automatic interconnection of theservice conduits, comprising a conduit connector member associated witheach coupling head and displaceable relative to the head in a directioninclined to the frontal impact face thereof, and means responsive to theapproach to coupling of the two cooperating coupling heads to effectrelative movement between the connector members and the respectivecoupling heads whereby operative interengagement of said connectormembers is effected only after impact of the two frontal impact faces ofthe coupling heads has occurred; said means for efiecting relativemovement between the connector member comprise means for effecting aninitial movement in which the connector member of one head is advancedtowards the connector member of the other head as the two heads firstengage, stop means for halting relative movement of the connector memberwhile impact between the frontal impact faces of the coupling headsoccurs, and means for effecting a final movement of the two connectormembers into engagement with each other.

2. In an automatic railway vehicle coupling having interengageablecoupling heads with frontal impact faces, and associated serviceconduits, a device for effecting automatic interconnection of theservice conduits, comprising a conduit connector member associated witheach coupling head and displaceable relative to the head in a directioninclined to the frontal impact face thereof, and means responsive to theapproach to coupling of the two cooperating coupling heads to effectrelative movement between the connector members and the respectivecoupling heads whereby operative intel-engagement of said connectormembers is effected only after impact of the two frontal impact faces ofthe coupling heads has occurred; said means for effecting relativemovement between the connector member and its respective coupling headcomprises an operating lever pivoted at one end to the respective headand pivotally engaging the respective connector member at its other end,a sensing lever pivoted between its ends to the coupling head, saidsensing lever having one arm arranged to cooperate, throughout theapproach of the coupling head into interengagement with a cooperatingcoupling head, with a projection on the cooperating head, and furtherhaving an arm, a resilient connection between the arm and the operativelever whereby movement may be transmitted to the operating lever fromthe sensing lever, a movable stop member which in a blocking positionlimits angular movement of the operating lever after an initial movementupon the initial engagement of the sensing lever by the cooperatingcoupling head, and means releasing the stop member from its blockingposition to permit a final movement of the operating lever and of theconnector member under the action of said resilient connection afterimpact of the coupling heads has occurred.

3. Device according to claim 2, wherein the means releasing the stopmember from its blocking position comprise an arm of the sensing leverwhich, upon displacement of the sensing lever by the coupling headengaged therewith following impact of the two coupling heads, displacesthe stop member from its blocking position.

4. Device according to claim 3, wherein the stop member comprises a stoplink having at one end a pin and slot lost motion connection to therespective operating lever and having at its other end a pivotconnection the respective coupling head including a toggle link,resilient means biassing the toggle link into a position in which itholds the stop link in its blocking position, the said am of the sensinglever engaging the stop link intermediate its ends upon movement of thesensing lever following impact of the two cooperating coupling heads todisplace the stop link so as to release the toggle formed by the stoplink and the toggle link and permit movement of the stop link from itsblocking position.

5. Device according to claim 2, wherein the stop member comprises a stoplever pivoted at one end to the coupling head and carrying at its otherend a hooklike tooth and the operating lever has an arm provided with ahooked end, and including a biassing spring urging the stop lever into ablocking position in which said tooth engages the hooked end of saidarm.

6. Device according to claim 4, wherein the means releasing the stoplever from its blocking position comprises a plunger mounted for slidingmovement in the respective coupling head and engageable directly by theother coupling head after impact of the two heads.

1. In an automatic railway vehicle coupling having interengageablecoupling heads with frontal impact faces, and associated serviceconduits, a device for effecting automatic interconnection of theservice conduits, comprising a conduit connector member associated witheach coupling head and displaceable relative to the head in a directioninclined to the frontal impact face thereof, and means responsive to theapproach to coupling of the two cooperating coupling heads to effectrelative movement between the connector members and the respectivecoupling heads whereby operative interengagement of said connectormembers is effected only after impact of the two frontal impact faces ofthe coupling heads has occurred; said means for effecting relativemovement between the connector member comprise means for effecting aninitial movement in which the connector member of one head is advancedtowards the connector member of the other head as the two heads firstengage, stop means for halting relative movement of the connector memberwhile impact between the frontal impact faces of the coupling headsoccurs, and means for effecting a final movement of the two connectormembers into engagement with each other.
 2. In an automatic railwayvehicle coupling having interengageable coupling heads with frontalimpact faces, and associated service conduits, a device for effectingautomatic interconnection of the service conduits, comprising a conduitconnector member associated with each coupling head and displaceablerelative to the head in a direction inclined to the frontal impact facethereof, and means responsive to the approach to coupling of the twocooperating coupling heads to effect relative movement between theconnector members and the respective coupling heads whereby operativeinterengagement of said connector members is effected only after impactof the two frontal impact faces of the coupling heads has occurred; saidmeans for effecting relative movement between the connector member andits respective coupling head comprises an operating lever pivoted at oneend to the respective head and pivotally engaging the respectiveconnector member at its other end, a sensing lever pivoted between itsends to the coupling head, said sensing lever having one arm arranged tocooperate, throughout the approach of the coupling head intointerengagement with a cooperating coupling head, with a projection onthe cooperating head, and further having an arm, a resilient connectionbetween the arm and the operative lever whereby movement may betransmitted to the operating lever from the sensing lever, a movablestop member which in a blocking position limits angular movement of theoperating lever after an initial movement upon the initial engagement ofthe sensing lever by the cooperating coupling head, and means releasingthe stop member from its blocking position to permit a final movement ofthe operating lever and of the connector member under the action of saidresilient connection after impact of the coupling heads has occurred. 3.Device according to claim 2, wherein the means releasing the stop memberfrom its blocking position comprise an arm of the sensing lever which,upon displacement of the sensing lever by the coupling head engagedtherewith following impact of the two coupling heads, displaces the stopmember from its blocking position.
 4. Device according to claim 3,wherein the stop member comprises a stop link having at one end a pinand slot lost motion connection to the respective operating lever andhaving at its other end a pivot connection the respective coupling headincluding a toggle link, resilient means biassing the toggle link into aposition in which it holds the stop link in its blocking position, thesaid arm of the sensing lever engaging the stop link intermediate itsends upon movement of the sensing lever following impact of the twocooperating coupling heads to displace the stop link so as to releasethe toggle formed by the stop link and the toggle link and permitmovement of the stop link from its blocking position.
 5. Deviceaccording to claim 2, wherein the stop member comprises a stop leverpivoted at one end to the coupling head and carrying at its other end ahooklike tooth and the operating lever has an arm provided with a hookedend, and including a biassing spring urging the stop lever into ablocking position in which said tooth engages the hooked end of saidarm.
 6. Device according to claim 4, wherein the means releasing thestop lever from its blocking position comprises a plunger mounted forsliding movement in the respective coupling head and engageable directlyby the other coupling head after impact of the two heads.